Leetcode 2386. Find the K-Sum of an Array

Given an integer array nums (n up to 1e5) and k ≤ min(2000, 2^n), return the k-th largest subsequence sum (the empty subsequence counts as 0). The core challenge is to avoid enumerating all 2^n sums and instead exploit the array's value structure to efficiently generate only the top-k subsequence sums.